This is a working overview of deamidation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-28. Anything still debated is marked as such rather than presented as settled.
Both receptors are class B G protein-coupled receptors that signal largely through Gs-mediated cyclic AMP production. Activation within pancreatic islets increases glucose-dependent insulin secretion and suppresses glucagon release when glucose is elevated. Outside the pancreas, signaling in the central nervous system and gut appears to influence appetite and gastric emptying. The relative contribution of each receptor to observed clinical effects remains under investigation, and the two pathways are not simply additive in practice.
Reported outcomes in large trials include dose-dependent weight reduction and improvements in glycemic markers over periods ranging from several months to more than a year. Whether the compound alters long-term cardiovascular or renal outcomes is being examined in dedicated outcome studies, so those questions remain open. Labeling describes gastrointestinal effects such as nausea and diarrhea, which tend to appear during dose escalation. Discontinuation rates and the durability of effects after treatment stops vary across study populations and are still debated.
Tirzepatide is a synthetic peptide developed as a dual agonist at the glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptors. Its structure is built on a GIP-derived backbone with non-natural amino acid substitutions and a fatty diacid side chain that promotes albumin binding and slows clearance. That modification supports once-weekly subcutaneous dosing. Registrational trial programs reported reductions in body weight and glycated hemoglobin alongside the drug's glycemic effects.
Tirzepatide is a synthetic peptide that activates both the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. This dual agonist profile distinguishes it from earlier incretin-based compounds that act on a single receptor. The molecule was engineered from the native GIP sequence and carries several non-natural residues that slow enzymatic breakdown. Researchers designed it to combine the insulinotropic effects of GIP signaling with the appetite and gastric-emptying effects associated with GLP-1 activation.
Development of tirzepatide took place under a research program that sought to test whether simultaneous engagement of two incretin receptors would produce greater metabolic effects than single-receptor agonism. Clinical trials were organized into the SURPASS series for type 2 diabetes and the SURMOUNT series for obesity and weight management. Regulatory clearance for type 2 diabetes came in 2022 in the United States, followed by approval for chronic weight management in 2023. The trial programs reported reductions in glycated hemoglobin and body weight relative to comparators, though long-term cardiovascular and durability data continue to accumulate.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic 39-residue peptide | GIP-derived backbone with non-natural residues |
| Molar mass | Approximately 4.8 kDa | Peptide chain plus linker and lipid modifications |
| Appearance | White to off-white powder | Typical of lyophilized research material |
| Solubility | Soluble in water and aqueous buffer | Practically insoluble in nonpolar solvents |
| Storage temperature | Typically −20 °C for dry powder | Solutions usually held at 2–8 °C short term |
Stability depends strongly on physical form. The dry powder is generally regarded as stable for extended periods when held at or below minus twenty degrees Celsius in a sealed, desiccated container. In solution, degradation pathways include deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation. Reaction rates for these pathways rise with temperature. Repeated freezing and thawing of solutions promotes aggregation, and light exposure can accelerate some oxidative changes. Buffer composition and pH influence which pathway dominates at a given temperature.
Regulatory and quality discussions place the peptide within established guidance for synthetic peptides and biologics. Forced degradation studies, in which samples are exposed to heat, acid, base, peroxide, and light, identify likely degradation products and validate the selectivity of analytical methods. Reference standards allow comparison across laboratories and production batches. Purity specifications reported in the literature usually combine chromatographic purity with mass confirmation. Which impurity thresholds are meaningful for long-term behavior is still debated, and no single universal specification has been adopted across all jurisdictions.
Routine characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity assessment, usually with ultraviolet detection near 214 nanometers. Intact mass measurement by liquid chromatography coupled to mass spectrometry confirms molecular identity against a theoretical value. Sequence-level confirmation uses enzymatic digestion followed by tandem mass spectrometry, an approach known as peptide mapping. Amino acid analysis gives an independent check on composition. Circular dichroism spectra are used to estimate helical content in aqueous buffer.
Clinical development proceeded through large phase 3 programmes in type 2 diabetes and in obesity or overweight with at least one weight-related comorbidity. Regulatory approvals followed in several jurisdictions for both indications. Weekly subcutaneous dosing reflects an elimination half-life of roughly five days. Open questions include the durability of metabolic effects after treatment stops, long-term cardiovascular and hepatic outcomes beyond completed trials, and whether the dual mechanism confers benefits independent of total receptor occupancy. Published literature continues to expand on these points. Substantial uncertainty remains about interindividual variability in response.
Tirzepatide is a synthetic linear peptide of 39 amino acids that acts as a dual agonist at the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. Its sequence derives from native GIP but incorporates non-natural residues and a C20 fatty diacid moiety linked to a lysine side chain. The lipophilic chain promotes albumin binding, which slows renal clearance and extends circulation time. The unmodified peptide has a molecular formula of C225H348N48O68 and a molecular mass near 4,813 daltons.
Receptor activation by tirzepatide raises intracellular cyclic AMP through Gs-coupled signalling at both targets. At the GLP-1 receptor the downstream effect includes glucose-dependent insulin release, suppressed glucagon secretion, delayed gastric emptying, and reduced appetite signalling in the hypothalamus. GIP receptor engagement adds insulinotropic activity and appears to influence lipid handling in adipose tissue. Because both receptors are stimulated at the same time, the pharmacological profile differs from that of selective GLP-1 receptor agonists, and the relative contribution of each arm remains an area of active investigation.
Degradation pathways for tirzepatide include deamidation, oxidation, and aggregation, which are common for therapeutic peptides. These processes can be monitored by size-exclusion chromatography (SEC) for aggregates and ion-exchange chromatography for charge variants. Forced degradation studies under acidic, basic, oxidative, and thermal stress help identify potential impurities. The exact stability profile depends on formulation, concentration, and container-closure system.
Analytical characterization of tirzepatide typically employs reversed-phase high-performance liquid chromatography (RP-HPLC) for purity assessment and peptide mapping. Mass spectrometry, often coupled with electrospray ionization, confirms molecular weight and sequence integrity. Amino acid analysis and capillary electrophoresis may also be used to detect impurities or degradation products. These methods are essential for batch release and stability studies.
Structure-activity work shows that fatty acid length, linker chemistry and the position of acylation all influence albumin affinity and receptor potency. Plasma protein binding exceeds 99 percent, which restricts distribution and slows renal clearance. Degradation proceeds largely through general proteolysis and fatty acid oxidation rather than cytochrome P450 metabolism, so exposure to common oxidative drug interactions is limited. Whether these clearance routes vary meaningfully between individuals is not fully established.
The molecule is a synthetic 39-amino-acid peptide whose backbone derives from the sequence of human glucose-dependent insulinotropic polypeptide, with several substitutions that raise metabolic stability and shift receptor preference. A C20 fatty diacid is attached through a short linker to a lysine side chain, a modification that increases binding to serum albumin. The reported monoisotopic mass is approximately 4813 Da. Near neutral pH the peptide carries a net negative charge, and the lipid tail makes the molecule markedly more hydrophobic than the unmodified parent sequence.
Dual agonism at the GIP and GLP-1 receptors underlies the observed pharmacology. Activation of GLP-1 receptors raises glucose-dependent insulin release, lowers glucagon secretion, slows gastric emptying and reduces appetite. GIP receptor activation contributes additional effects on adipose tissue and on energy balance, and the combined action on appetite appears larger than either pathway alone in animal models. Signalling bias and the relative contribution of each receptor arm to weight-related effects remain areas of active investigation.
{\displaystyle (\mathbf {g} _{i},\nabla p)=-{\bigl (}\mathbf {g} _{i},\left(\mathbf {u} \cdot \nabla \right)\mathbf {u} _{j}{\bigr )}-\nu \left(\nabla \mathbf {g} _{i}:\nabla \mathbf {u} _{j}\right)+\left(\mathbf {g} _{i},\mathbf {f} ^{I}\right)}
777 was the owner of low-cost carrier Flair Airlines. In June 2022, the Canadian Transportation Agency ruled that Flair is a Canadian airline and can fly domestically, as 777 owns 25% of the shares and had limited its influence on the board since the beginning of the CTA investigation. On March 11, 2023, Airborne Capital Ltd. seized four of its planes operated by Flair over alleged non-payment. In a press conference, Flair CEO Stephen Jones suggested the seizures were motivated by competitors, and that the airline owed around US$1 million on the leases, and was in the process of making payment when the seizures occurred. The lessor, Airborne alleged that Flair had repeatedly missed payments amounting to several millions of dollars over a period of five months. Flair used other aircraft to continue to operate its schedule. In January 2024, it was reported that the lessors had filed claims at the UK High Court for costs and that there had been outstanding payments of $1.8 million on the four aircraft when notice of default was served. In August 2024, interim CEO Maciej Wilk said that 777's stake in Flair was down to 10% and the company's involvement was mostly as a lender, having no presence in the boardroom.
== Diagnosis == Detection of APCA (anti-parietal cell antibodies), anti-intrinsic factor antibodies (AIFA), and Helicobacter pylori (HP) antibodies in conjunction with serum gastrin are effective for diagnostic purposes.
Sources: en.wikipedia.org
=== Selected articles === Falk, Ronald J.; Jennette, J. Charles (1988). "Anti-Neutrophil Cytoplasmic Autoantibodies with Specificity for Myeloperoxidase in Patients with Systemic Vasculitis and Idiopathic Necrotizing and Crescentic Glomerulonephritis". New England Journal of Medicine. 318 (25): 1651–1657. doi:10.1056/NEJM198806233182504. PMID 2453802. Falk, R. J.; Terrell, R. S.; Charles, L. A.; Jennette, J. C. (1990). "Anti-neutrophil cytoplasmic autoantibodies induce neutrophils to degranulate and produce oxygen radicals in vitro". Proceedings of the National Academy of Sciences. 87 (11): 4115–4119. Bibcode:1990PNAS...87.4115F. doi:10.1073/pnas.87.11.4115. PMC 54058. PMID 2161532. Jennette, J. Charles; Falk, Ronald J.; Andrassy, Konrad; Bacon, Paul A.; Churg, Jacob; Gross, Wolfgang L.; Hagen, E. Christiaan; Hoffman, Gary S.; Hunder, Gene G.; Kallenberg, Cees G. M.; McCluskey, Robert T.; Sinico, R. Alberto; Rees, Andrew J.; Es, Leendert A. Van; Waldherr, Rüdiger; Wiik, Allan (1994). "Nomenclature of Systemic Vasculitides". Arthritis & Rheumatism. 37 (2): 187–192. doi:10.1002/art.1780370206. PMID 8129773. Jennette, J. Charles; Falk, Ronald J. (1997). "Small-Vessel Vasculitis". New England Journal of Medicine. 337 (21): 1512–1523. doi:10.1056/NEJM199711203372106. PMID 9366584. Xiao, Hong; Heeringa, Peter; Hu, Peiqi; Liu, Zhi; Zhao, Minglang; Aratani, Yasuaki; Maeda, Nobuyo; Falk, Ronald J.; Jennette, J. Charles (2002). "Antineutrophil cytoplasmic autoantibodies specific for myeloperoxidase cause glomerulonephritis and vasculitis in mice". Journal of Clinical Investigation.
== Biological activity == 2-Aminoisobutyric acid is not one of the proteinogenic amino acids and is rather rare in nature (cf. non-proteinogenic amino acids). In the context of cell-free protein synthesis 2-aminoisobutyric acid is compatible with ribosomal elongation of peptide synthesis. Flexizymes and an engineered tRNA body enhance the affinity of aminoacylated Aib-tRNA species to elongation factor P. The result was an increased incorporation of Aib into peptides in a cell free translation system. Iqbal et al.. used an alternative approach of creating an editing deficient valine—tRNA ligase to synthesize aminoacylated Aib-tRNAVal. The aminoacylated tRNA was subsequently used in a cell-free translation system to yield Aib-containing peptides.
=== Therapeutic resistance and tumor aggressiveness === In pancreatic ductal adenocarcinoma (PDAC), ITGA1 promotes tumor progression by regulating tumor cell survival, extracellular matrix (ECM) signaling, and chemotherapy resistance. ITGA1-mediated signaling enhances epithelial-mesenchymal transition (EMT), metastatic potential, and resistance to gemcitabine, a commonly used chemotherapeutic agent for PDAC. Inhibition of ITGA1 increases sensitivity to chemotherapy, suggesting that targeting ITGA1-dependent ECM signaling may improve therapeutic responses in aggressive pancreatic cancer. In PDAC, ITGA1 marks and functionally regulates AIDH1-high pancreatic cancer cells with stem-like properties. These ITGA1-positive tumor-initiating cells lead to metastasis, therapy resistance, as well as poor prognosis. Inhibition of ITGA1 reduces the tumor-initiating ability of these cells, suggesting that ITGA1 may represent a strategy for targeting resistant cancer populations in PDAC.
The epithelium of the ectocervix (the portion of the uterine cervix extending into the vagina) is an extension of, and shares a border with, the vaginal epithelium. The vaginal epithelium is made up of layers of cells, including the basal cells, the parabasal cells, the superficial squamous flat cells, and the intermediate cells. The basal layer of the epithelium is the most mitotically active and reproduces new cells. The superficial cells shed continuously and basal cells replace them. Estrogen induces the intermediate and superficial cells to fill with glycogen. Cells from the lower basal layer transition from active metabolic activity to death (apoptosis). In these mid-layers of the epithelia, the cells begin to lose their mitochondria and other organelles. The cells retain a usually high level of glycogen compared to other epithelial tissue in the body. Under the influence of maternal estrogen, the vagina of a newborn is lined by thick stratified squamous epithelium (or mucosa) for two to four weeks after birth. Between then to puberty, the epithelium remains thin with only a few layers of cuboidal cells without glycogen. The epithelium also has few rugae and is red in color before puberty. When puberty begins, the mucosa thickens and again becomes stratified squamous epithelium with glycogen-containing cells, under the influence of the girl's rising estrogen levels. Finally, the epithelium thins out from menopause onward and eventually ceases to contain glycogen, because of the lack of estrogen.
Sources: en.wikipedia.org
In early November 2020, Israel Hadassah Medical Center director-general Zeev Rotstein stated that Hadassah's branch in Moscow's Skolkovo Innovation Center was collaborating on a phase III clinical trial. The ongoing phase III study is a randomised, double-blind, placebo-controlled, multi-centre clinical trial involving 40,000 volunteers in Moscow, and is scheduled to run until May 2021. In 2020–2021, phase III clinical studies were also being conducted in Belarus, UAE, India, Kazakhstan and Venezuela. On 13 April 2021, India's health ministry said its drug regulator had found that safety and immunogenicity data from a local trial of Sputnik V coronavirus vaccine was comparable to that of a late-stage trial done in Russia.
For instance, knockdown of ACP reduces ceramide levels, whereas loss of the terminal mtFAS enzyme MECR results in ceramide accumulation. Importantly, mtFAS function extends to the regulation of immune cell metabolism. CRISPR/Cas9 screens have identified mtFAS genes—especially Mecr, Mcat, and Oxsm—as key regulators of T cell metabolism. While MECR is not required for naive T cell maintenance, its loss in activated T cells impairs proliferation, survival, and differentiation. MECR deficiency disrupts mitochondrial respiration, alters TCA cycle activity, and increases ferroptosis sensitivity, ultimately reducing T cell fitness and inflammatory capacity.
== Branches of botany == Botany is divided along several axes. Some subfields of botany relate to particular groups of organisms. Divisions related to the broader historical sense of botany include bacteriology, mycology (or fungology), and phycology – respectively, the study of bacteria, fungi, and algae – with lichenology as a subfield of mycology. The narrower sense of botany as the study of embryophytes (land plants) is called phytology. Bryology is the study of mosses (and in the broader sense also liverworts and hornworts). Pteridology (or filicology) is the study of ferns and allied plants. A number of other taxa of ranks varying from family to subgenus have terms for their study, including agrostology (or graminology) for the study of grasses, synantherology for the study of composites, and batology for the study of brambles. Study can also be divided by guild rather than clade or grade. For example, dendrology is the study of woody plants. Many divisions of biology have botanical subfields. These are commonly denoted by prefixing the word plant (e.g. plant taxonomy, plant ecology, plant anatomy, plant morphology, plant systematics), or prefixing or substituting the prefix phyto- (e.g. phytochemistry, phytogeography). The study of fossil plants is called palaeobotany. Other fields are denoted by adding or substituting the word botany (e.g. systematic botany). Phytosociology is a subfield of plant ecology that classifies and studies communities of plants.
==== Hermaphroditism ==== Some teleost species are hermaphroditic, which can come in two forms: simultaneous and sequential. In the former, both spermatozoa and eggs are present in the gonads. Simultaneous hermaphroditism typically occurs in species that live in the ocean depths, where potential mates are sparsely dispersed. Self-fertilisation is rare and has only been recorded in two species, Kryptolebias marmoratus and Kryptolebias hermaphroditus. With sequential hermaphroditism, individuals may function as one sex early in their adult life and switch later in life. Species with this condition include parrotfish, wrasses, sea basses, flatheads, sea breams and lightfishes. Protandry is when an individual starts out male and becomes female while the reverse condition is known as protogyny, the latter being more common. Changing sex can occur in various contexts. In the bluestreak cleaner wrasse, where males have harems of up to ten females, if the male is removed the largest and most dominant female develops male-like behaviour and eventually testes. If she is removed, the next ranking female takes her place. In the species Anthias squamipinnis, where individuals gather into large groups and females greatly outnumber males, if a certain number of males are removed from a group, the same number of females change sex and replace them. In clownfish, individuals live in groups and only the two largest in a group breed: the largest female and the largest male. If the female dies, the male switches sexes and the next largest male takes his place.
Zipline originated from Romotive, a company founded in 2011 by Keller Rinaudo Cliffton that produced an iPhone-controlled robot. Romotive ceased operations in 2014, after which Rinaudo, Ryan Oksenhorn, William Hetzler, and Keenan Wyrobek began developing a fixed-wing drone platform intended for medical delivery. This effort became the basis for Zipline. The company began operations in Rwanda in October 2016 following a government agreement to deliver blood and medical supplies to rural clinics from a centralized distribution center. A second Rwandan center opened in 2018 as the scope of deliveries expanded to include routine vaccines and essential medicines. Zipline launched operations in Ghana on April 24, 2019 under a government contract that provided drone delivery services to public-sector health facilities. The program later expanded to multiple distribution centers serving additional regions. Beginning in 2020, the company participated in regulatory programs, including the FAA type-certification process for delivery drones in the United States. It also deployed temperature-controlled payload systems to support delivery of vaccines requiring cold-chain conditions, including during COVID-19 vaccination campaigns in parts of Africa. From 2022 onward, Zipline initiated operations outside Africa, including a partner-operated distribution center in Japan and limited pilot projects in the United States. It also introduced a new platform aimed at home deliveries in denser urban and suburban environments.
Sources: en.wikipedia.org
It acts as an agonist at both the GIP and GLP-1 receptors, two related class B G protein-coupled receptors. This dual activity distinguishes it from single-receptor GLP-1 agonists. The clinical consequences of engaging both receptors are still being characterized.
It is given by subcutaneous injection, generally on a weekly schedule. Dosing usually begins low and increases in steps to limit gastrointestinal side effects. Formulated product is supplied as a ready-to-use pen or vial in most markets.
No. Receptor engagement is documented, but how central appetite circuits, gut signals, and insulinotropic effects combine is incompletely resolved. Investigators continue to separate GIP-driven from GLP-1-driven contributions in animal and human models.
It binds and activates both the GIP and GLP-1 receptors, making it a dual incretin receptor agonist. Single-receptor GLP-1 agonists act on one target only. The dual profile is the defining pharmacological feature of the molecule.